Fuel limiting device

ABSTRACT

A fuel limiting device for an internal combustion engine having a governor which governor is adapted to move a fuel-adjusting member to an overfueling position during starting of the engine and to a normal fuel supply operating range after the engine has started. The limiting device is disposed in a non-interfering relation to the fuel-adjusting member during engine starting and is movable in response to engine operation to a position which provides a positive stop for the fuel-adjusting member to preclude movement of the adjusting member to the overfueling position during lugging of the engine or other high-load conditions to minimize smoke emissions.

United States Patent 1 91 Gates et al. Dec. 11, 1973 [54] FUEL LIMITING DEVICE 3,532,082 10/1970 Clause et al. 123/140 R [75] Inventors: Marvin A. Gates, Chillicothe; Mark Sommars Peoria, both of m Zztmary Exglmmer-i-LzurencetMl. Goodridge orneyarren rauss e a [73] Assignee: Caterpillar Tractor (10., Peoria, 111. [22] Filed: Mar. 20, 1972 [57] ABSTRACT [21] Appl..No.: 236,382 A fuel limiting device for an internal combustion engine having a governor which governor is adapted to move a fuel-adjusting member to an overfueling posi- [22] (gr 123/140 R, 3 9 80: tion during starting of theengine and to a normal fuel d 139 ST supply operating range after the engine has started. e 0 can R 140 3 179 1 The limiting device is disposed in anon-interfering relation to the fuel-adjusting member during engine starting and is movable in response to engine opera- [56] References (med tion to a position which provides a positive stop for UNITED STATES PATENTS v the fuel-adjusting member to preclude movement of 3,577,967 5/1971 Staudt 123/140 FG the adjusting member to the overfueling position dur- 3,204,624 9/1965 Rutenberg et al 123/139 ST ing lugging of the engine or other high-load conditions 3,557,764 1/1971 Knight 23/140 F6 to minimize Smoke emissions 3,058,455 10/1962 l-lofer et al 123/140 R 3,145,624 8/1964 5 Claims,-2 Drawing Figures Parks et a1, 123/140 R FUEL LIMITING DEVICE BACKGROUND OF THE INVENTION conventionally,"governors are utilized to position a fuelpump feed rack of a compression ignition engine to maintain a constant engine speed. Such governors are shown in US. Pats. Nos. 3,l45,624 and 3,532,082 to Parks et al, and Clouse, respectively, both of common assignment herewith. With such governors, when engine load increases, engine speed tends to decrease to cause the automatic advancement of the fuel rack to supply more fuel to the engine. When engine loading decreases, engine speed increases with a consequent retraction of the fuel pump feed rack to reduce fuel supply to the engine.

To aid in starting the engine, the fuel pump feed rack is moved by a spring in the governor mechanism to the full-travel, maximum-supply position, commonly known as the overfuel position, to provide maximum fuel flow during start-up.

One of the undesirable aspects associated with conventional governing systems utilizing such a start-up capability is the creation of highly objectionable exhaust smoke when the fuel pump feed rack is advanced to the overfueling position when the engine is operating and start-up conditions are simulated. Under certain engine conditions such as lugging, engine speed decreases to a point where the governor advances the fuel pump feed' rack to the overfueling position to cause the injection of a disproportionate amount of fuel relative to the amount of air available in the engine combustion chambers. This results in the incomplete combustion of such excess fuel which, particularly when utilizing hydrocarbon fuels, results in the formation of free liquid and smoke in the exhaust emission and the deposition of carbon particles on engine parts.

OBJECTS OF THE INVENTION It is an object of this invention to provide an improved fuel limiting device for the fuel injection system of an internal combustion engine.

Another object of this invention is to provide an improved fuel limiting device which prevents the movement of the fuel-adjusting member ofa fuel pump to an overfueling position subsequent to engine start-up.

A further object of this invention is to provide a fuel limiting device which utilizes a movable stop member whichmember is movable in response to engine operation to a position which limits movement of the fuel pump feed rack to an overfueling positi'onduring engine lugging conditions to minimize smoke emission and carbon deposition.

Other objects and advantages of the present invention will become more readily apparent upon reference to the accompanying drawings and following description.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal vertical section through the fuel limiting device of the present invention as asso- DETAILED DESCRIPTION Referring more particularly to the drawings, the fuel limiting device of the present invention is indicated by the reference numeral 10 and is shown in association with a governor mechanism 11 for an internal combustion engine (not shown). The governor mechanism is of the type described in the above-noted patents toParks et al, and Clouse. It is contained within a housing 12 which is secured to one end of a fuel pump housing 13. The governor mechanism provides for the longitudinal positioning of a fuel-adjusting member or feed rack 14 which is disposed within the pump housing. The fueladju'sting member has rack teeth 16 formed thereupon for meshing with the teeth of a gear 17 which is part of fuel control assemblage of a fuel pump 18. There is one such pump provided for each engine cylinder.

As viewed in FIG. 1, the left-hand end of the fueladjusting member includes a flange portion 19 which is connected by means of a groove to part of a piston member 21 which is part of a servo system shown generally at 22. The piston member is disposed for reciprocal movement within a cylinder 23 and a sleeve 24, both of which are secured to the pump housing by suitable means. The piston member 21 has a flange portion 27 intermediate its length which forms an annular cavity 28 with the left-hand end of the cylinder 23 and which forms an annular cavity 29 with the right-hand end of the cylinder and the sleeve 24. The piston member is formed with a bore 31 and with radiallyextending passage means 32 and 33 on opposite sides of the flange portion'27 which communicate the bore with the annular cavities 28 and 29, respectively. A cross-passage means 34- is formed within the pump housing. It intersects with a passage'76 and communicates with the annular cavity 29 and with a source of fluid (not shown) which becomes pressurized in response to engine operation. Such a fluid, for illustrative purposes, could be engine lubrication oil.

A control valve means 37 is disposed for reciprocal movement within a bore 31 of the piston member 21 and has an annular recess 38 formed thereupon, as shown. The control valve means has a flange portion 39 formed at'the end thereof whichis adjacent to the flange portion 19 of the fuel-adjusting member 14. The opposite end of the valve means is secured to an adapter means 41 by means of a pin 42 or other suitable connector. Theadapter means carries a thrust plate 43 thereupon.

The governor mechanism includes a pair of flyweights 46 which are pivotally mounted upon a cylindrical carrier member 47 by pins 48 or the like. Each flyweight has a radially inwardly extending arm portion 49 adapted to make contact with the thrust plate '43. The carrier member is mounted for rotation upon the cylinder 23 and is formed with gear means 51 in constant mesh with a drive gear 52 which is secured to a shaft 53 which, in turn, forms part of a timing gear train of the engine.

The governor mechanism further includes a bifurcated control lever means 56 which engages a spring seat 57 which seat is slidably mounted upon a fixed support member 58. A sleeve member 59 is telescopically axially slidably mounted between the spring seat and the support member and has a shoulder portion 61 which is adapted for abutting engagement with a shoulder portion 62 of the spring seat 57. A high-idle spring means 63 is disposed coaxially about the sleeve member 59 and is retained in a preloaded state between the spring seat and a ring 66 which ring is constrained by means of a snap ring 67. A low-idle spring means 68 is confined between the ring 66 and the adapter means 41.

The fuel limiting device includes a cylindrical bore 69 formed within the pump housing 13 coaxially with the fuel-adjusting member 14. The bore has an open end 71 and a closed end 72, as shown in FIG. 1. An orifice 73 is formed within the closed end of the bore and communicates said bore with a cavity 74 formed by the pump housing 13. Port 76 is formed as a part of the pump housing with an opening into the bore 69 intermediate the closed and open ends thereof.

A piston means 77 is disposed for reciprocal movement within the bore and has an axial bore 78 formed therein. The fuel-adjusting member 14 is disposed for reciprocal movement within the bore 78. A compression spring 79 is disposed within the cylindrical bore between the closed end thereof and the piston to urge said piston into abutting contact with the piston member 21 of servo system 22.

OPERATION The governor mechanism 11 functions to maintain a relatively constant, predetermined engine operating speed for any given operator setting by adjusting the position of the fuel-adjusting member 14 as loading on the engine varies. Any predetermined speed setting is obtained by the manual positioning of the control lever 56 to provide a given preload on the springs 63 and 68. Such preloadings act against the force imposed by the flyweights 46 which move radially outwardly under the influence of centrifugal force. To increase the engine speed, the lever is rotated in a counterclockwise direction. This results in the movement of fuel-adjusting member 14 toward the right in amanner to be hereinafter explained. Clockwise rotation of the control lever results in the movement of the fuel-adjusting member toward the left in a manner which will decrease engine speed. I

Counterclockwise rotation of the control lever 56 against the spring seat 57 compresses the governor springs 63 and 68 and thereby urges the adapter means 41 and control valve means 37 rightwardly against the force, if any, imposed by the flyweights 46. Rightward movement of the control valve means causes movement of the fuel-adjusting member 14 in the following manner. Fluid under pressure is supplied to the control valve through the passage 34, passage 76, annular cavity 29, and radial passages 33. Such movement of the control valve means opens communication between the radial passages 33 and 32 by way of the annular recess 38 formed by a reduced portion of the control valve. This communication allows fluid to flow into the annular cavity 28. Fluid in annular cavity 28 creates a greater force on the left side of the flange portion 27 than on the right side thereof due to the relative sizes of the surface areas exposed to the fluid and causes movement of the piston 21 and the fuel-adjusting member rightwardly toward the full load position. When the desired speed is obtained, the force imposed by the flyweights balances the force imposed by the springs 63 and 68 and stops the rightward travel of the control valve. In this condition, flow of fluid through the passage 33 of the control valve is blocked to thereby prohibit further rightward movement of the pistion 21 and fuel-adjusting member.

When the load upon the engine is increased and the governing system is set within a selected operating range, engine speed tendsto decrease and this results in a corresponding reduction in the force imposed upon the flyweights 46 to thereby allow the springs 63 and 68 to move the adapter means 41 and control valve means 37 toward the right. As will be explained hereinafter, this tends to result in the movement of the fueladjusting member 14 to the right, in the manner previously described, to supply more fuel to the engine to maintain the desired engine speed.

When the load on the engine is reduced, engine speed increases and the force of the flyweights causes the adapter means and control valve to move toward the left. This leftward movement causes the piston 21 and, in turn, the fuel-adjusting member 14 to move toward the left to decrease the supply of fuel to the engme.

The governor mechanism 11 is shown in FIG. 1 in the engine start-up configuration. The fuel-adjusting member 14 is disposed in an overfuel position and the valve means 37 is rightwardly disposed. Such a configuration is obtained by rotating the control lever 56 in a counterclockwise direction to load the springs 63 and 68. This causes movement of the adapter means 41, control valve 37, piston 21, fuel-adjusting member 14, and piston 77 rightwardly against the bias of the spring 79. In such a disposition, the piston 77 blocks communication between the bore 78 and the passage 76 as shown in FIG. 1.

After the engine has been started, the flyweights 46 swing outwardly to cause the arms 49 to act against the thrust plate 43 and the adapter means 41. Flyweight force compresses the spring 68 and moves the adapter means 41, valve means 37, piston member 21 and fueladjusting member 14 leftwardly to within the operating range of positions discussed above. Such leftward movement of piston member 21 allows the spring 79 to move the piston 77 leftwardly until it abuts the sleeve member 24, as shown in FIG. 2. This opens communication between the passage 76 and the bore 78 to allow fluid from cross passage 34 to enter the bore. The orifice 7.3 is dimensioned to permit only a minute flow of fluid there-through so that the fluid in the bore remains pressurized to substantially maintain the piston 77 in the leftward position.

With the system disposed within the operating range, the piston member 21 and the fuel-adjusting member 14 are positioned leftwardly from the positions shown in FIG. 2. The fuel limiting device does not interfere with the operation of the governor mechanism in the operating range. The fuel-adjusting member is permitted to advance to the full load position on demand at which time the piston member 21 contacts the piston 77 as shown in FIG. 2 at 81. The force exerted upon the piston 77 by the pressurized fluid in bore 78 is greater than the force exerted by the springs 68 and 63 and thus the fuel-adjusting member is prohibited from moving to the overfuel position.

When the engine is shut down, the fluid pressure is relieved and the fluid within the bore 78 is exhausted through the orifice 73 as the springs 68 and 63 urge the control valve 37, piston member 21, fuel-adjusting member 14, and piston 77 toward the right against the bias of spring 79.

in view of the foregoing, it is readily apparent that the structure of the present invention provides an improved fuel limiting device which prevents undesired overfueling in an internal combustion engine by maintaining the fuel-adjusting member within its normal operating range of positions during normal operation. This is accomplished by providing a movable stop member which is movable in response to operation of the engine to a position providing a positive stop for the fuel-adjusting member to prevent movement thereof to the overfueling position.

While the invention has been described and shown with particular reference to the preferred embodiment, it will be apparent that variations and modifications might be possible within the spirit of the inventive concepts and that no limitation is intended, except by the scope of the appended claims.

What is claimed is:

1. In a fuel supply system for an engine having a fuel pumping means with a fuel-adjusting means associated therewith for regulating the amount of fuel supplied to the engine and wherein a governing means controls the position of said adjusting means to maintain a substantially constant predetermined engine speed; the improvement comprising fuel limiting means for selectively prohibiting movement of said fuel-adjusting means to a maximum fuel flow position when said engine is in operation while permitting movement of said fuel-adjusting means to said maximum fuel position prior to and during engine start-up, said fuel limiting means including movable stop means movable to a first position to permit the unrestrained movement of said adjusting means and movable to a second position under the influence of fluid pressure in response to engine operation for directly engaging and providing a positive stop for said adjusting means to preclude movement of said adjusting means to said maximum fuel position, said fuel limiting means having housing means and wherein said movable stop means include a piston member slidably disposed within a bore means formed within said housing means and being movable therein between said first and second position, and first passage means in said housing means for communicating said fluid under pressure to said bore means to actuate said piston member to said second position.

2. The invention of claim 1 wherein said governing means include an engine speed responsive governor which causes movement of said adjusting means to decrease fuel flow to said engine upon engine speed increases and to increase fuel flow to said engine upon engine speed decreases.

3. The invention of claim 1 further including resilient means disposed within said bore means for biasing said piston member toward said second position, said piston member being disposed to block said first passage means when in said first position and disposed to open said first passage means when in said second position to allow piston member actuating fluid to enter said bore means and to hold said piston member in said second position, said piston member in said second position being disposed in abutting engagement with said adjusting means to prevent movement thereof toward said maximum fuel position, said adjusting means being disposed to move said piston member toward said first position against the bias of said resilient means when said engine is inoperative. v

4. The invention of claim 1 wherein said piston member and said governing means are disposed for movement along a common axis.

5. The invention of claim 1 wherein said movable stop means include; a cylindrical bore formed within said housing and disposed coaxially with said fueladjusting means, said bore having an open end adjacent to said governing means and an opposite closed end, said first passage means being spaced axially from said closed end and communicating said bore with said fluid under pressure, and second passage means including an outlet orifice communicating with said closed end of said bore; said piston member being reciprocably mounted within said cylindrical bore and adapted to block said first passage means in said first position to close off communication between said fluid under pressure and said bore and adapted to open said first passage means in said second position to permit the entrance of pressurized fluid into said cylindrical bore to hold said piston member in said second position; and biasing means disposed within said bore between said closed end and said piston member to urge said piston member toward said governing means whereby said biasing means moves said piston member to said second position to permit said fluid to enter said bore to hold said piston member in said second position after said engine has started with said governing means being effective to move said piston member to said first position when said engine is shut down. 

1. In a fuel supply system for an engine having a fuel pumping means with a fuel-adjusting means associated therewith for regulating the amount of fuel supplied to the engine and wherein a governing means controls the position of said adjusting means to maintain a substantially constant predetermined engine speed; the improvement comprising fuel limiting means for selectively prohibiting movement of said fuel-adjusting means to a maximum fuel flow position when said engine is in operation while permitting movement of said fuel-adjusting means to said maximum fuel position prior to and during Engine start-up, said fuel limiting means including movable stop means movable to a first position to permit the unrestrained movement of said adjusting means and movable to a second position under the influence of fluid pressure in response to engine operation for directly engaging and providing a positive stop for said adjusting means to preclude movement of said adjusting means to said maximum fuel position, said fuel limiting means having housing means and wherein said movable stop means include a piston member slidably disposed within a bore means formed within said housing means and being movable therein between said first and second position, and first passage means in said housing means for communicating said fluid under pressure to said bore means to actuate said piston member to said second position.
 2. The invention of claim 1 wherein said governing means include an engine speed responsive governor which causes movement of said adjusting means to decrease fuel flow to said engine upon engine speed increases and to increase fuel flow to said engine upon engine speed decreases.
 3. The invention of claim 1 further including resilient means disposed within said bore means for biasing said piston member toward said second position, said piston member being disposed to block said first passage means when in said first position and disposed to open said first passage means when in said second position to allow piston member actuating fluid to enter said bore means and to hold said piston member in said second position, said piston member in said second position being disposed in abutting engagement with said adjusting means to prevent movement thereof toward said maximum fuel position, said adjusting means being disposed to move said piston member toward said first position against the bias of said resilient means when said engine is inoperative.
 4. The invention of claim 1 wherein said piston member and said governing means are disposed for movement along a common axis.
 5. The invention of claim 1 wherein said movable stop means include; a cylindrical bore formed within said housing and disposed coaxially with said fuel-adjusting means, said bore having an open end adjacent to said governing means and an opposite closed end, said first passage means being spaced axially from said closed end and communicating said bore with said fluid under pressure, and second passage means including an outlet orifice communicating with said closed end of said bore; said piston member being reciprocably mounted within said cylindrical bore and adapted to block said first passage means in said first position to close off communication between said fluid under pressure and said bore and adapted to open said first passage means in said second position to permit the entrance of pressurized fluid into said cylindrical bore to hold said piston member in said second position; and biasing means disposed within said bore between said closed end and said piston member to urge said piston member toward said governing means whereby said biasing means moves said piston member to said second position to permit said fluid to enter said bore to hold said piston member in said second position after said engine has started with said governing means being effective to move said piston member to said first position when said engine is shut down. 